Quant Hacks Day – Solve it in Seconds

Quantitative Aptitude is hard in most cases especially in exam like Banks and Insurance. Many Banks exam has two tier examination pattern i.e., Prelims and Mains. Most of them have changed their exam patterns and set a sectional timing of 20 minutes on each section. However Quant is important for every exam because proper strategy and enough practice can help you score full marks in this section. There may not be assurance in language section and you may stuck while solving reasoning questions but quants is a scoring subject and assures full marks if the calculation is correct.
So to help you ace the quants and to save your precious time during exam hours Adda247 providing some quant tricks to help aspirants   
Rule 1. Multiplication by 11

Example 1- 

24*11= 2_addition of (2+4) 4

hundred and ones digit is fixed, tens digit is sum of digits.
a) 2 always in hundred place
b) tens place- addition of digits
c) ones place- 4
Example 2- 


60* 11= 6 in hundred place, addition of digits in tens place, 0 in ones place= 660
Rule 2. Addition of interchange number 

Addition of interchange number= 11*(addition of digits)


Example-
1) 26+62
2) 68+86
Now addition of 26+62 be done
 =11*(2+6)= 88
For 68+86= 11*(6+8)= 11*14=154


3) 97+79+58+85+32+23= 11*[(addition of (9+7)+(5+8)+(3+2)]= 11*(16+13+5)=11*34=374 


multiplication by 11 refer to rule 1
Rule 3.Subtraction of Interchange Number


Subtraction of interchange Number= 9*( difference of digits)


Example- 
1) 26-62
2) 68-86
3) 86-68

Note – sign of a number is according to
For 26-62= 9*(4)=-36 … sign is according to sign with bigger number

For 68-86=9*(2)=-18….sign is according to sign with bigger number
for 86-68= 9*(2)=18…. sign is according to sign with bigger number
for 62-26=9*(4)=36.. sign is according to sign with bigger number


4) 34-43-29+92-68+86-79+97-62+26=9*[ (3-4)+(9-2)+(8-6)+(9-7)+(2-6)]=9 *[ -1+7+2+2-4]=9*6= 54
Rule 4. Combination of  addition and subtraction of  Interchangeable numbers



Eg1- 97+79+62-26+58+85+68-86+32+23=  [97+79, 58+85, 32+23]+[62-26, 68-86]

segregate addition of interchange number and subtraction of interchange number



for  [97+79, 58+85, 32+23]= 11*[(9+7)+(5+8)+(3+2)= 11*(16+13+5)=11*34=374

for [62-26, 68-86]= 9*[(6-2)+(6-8)=9*[4+(-2)]=9*2=18

=374+18= 392



Important- Above two types are used in average example-



Question- Average of 20 numbers is 20, we mistakenly take it as 85 but in actual it is 58. What is average now.




Solution- change in value= -85+58= apply Rule 3= 9*(-8+5)= 9*(-3)= -27


change in value = -27/20= -1.35


change in average= 20-1.35=18.65




Rule 5- Square of numbers with unit digit 5.

(25)^2= 2*(2+1)   25 always at unit place

(35)^2= 3*(3+1) 25 always in unit place =1225

(45)^2= 4*(4+1) 25=2025

(105)^2=11025

This rule is useful for square of numbers of unit digit 5.


Do It Yourself:



1. 44+89-64+78+44-98+46-87
2. 11*88

3. 11*123
4. 75*75